The influenza virus enigma

Abstract

Both seasonal and pandemic influenza continue to challenge both scientists and clinicians. Drug-resistant H1N1 influenza viruses have dominated the 2009 flu season, and the H5N1 avian influenza virus continues to kill both people and poultry in Eurasia. Here, we discuss the pathogenesis and transmissibility of influenza viruses and we emphasize the need to find better predictors of both seasonal and potentially pandemic influenza.

Figure 1. Spheres of Progress in influenza Research

Shown are the three major areas of influenza research: (1) the molecular basis of pathogenicity and transmission, (2) surveillance, and (3) therapies and pandemic preparedness. Points of overlap among the three circles illustrate how the findings in each area have implications for the other two areas. The major challenges within each area of research are noted around the periphery of that circle.

Figure 2. Molecular Basis of influenza Pathogenesis

The life cycle of the influenza virus begins with binding of the virus to sialic acid receptors on the surface of the host cell via the viral surface glycoprotein hemagglutinin (H). This step contributes to pathogenesis, transmission, and host range restriction. Replication of the eight negative-strand RNA segments that comprise the influenza genome is central to viral pathogenesis and could be a potential therapeutic target. The release of the virion from the host cell is a hallmark of successful completion of the influenza virus life cycle. Key molecular proteins and pathways that are activated during influenza virus infection of the host cell are also depicted. Potential host signal transduction factors are indicated in red.